1. Technical Field
The present disclosure relates to a frit sealing system and a method of manufacturing an organic light emitting display device by using the frit sealing system, and more particularly, to a frit sealing system and a method of manufacturing an organic light emitting display device by using the frit sealing system, which includes a pressure member that physically pressurizes a first substrate and a second substrate, thereby increasing adhesion of a frit disposed between a first substrate and a second substrate thereto.
2. Description of the Related Art
Recently, older style display devices have been replaced with thin flat display devices, which are portable. Of the types of flat display devices, electroluminescent display devices are active matrix-type display devices that are potential next generation display devices exhibiting wide viewing angles, high contrast, and fast response speeds. Also, compared with inorganic light emitting display devices, organic light emitting display devices having an emissive layer comprising organic materials exhibit advantageous luminance, driving voltage, and response speed, and a capability to display a wide color gamut.
An organic light emitting display device generally includes a structure comprising at least an organic layer including an emissive layer interposed between a first electrode and a second electrode. The first electrode is formed on a substrate, and serves as an anode injecting holes, and the organic layer is formed on a top surface of the first electrode. On the organic layer, the second electrode, serving as a cathode injecting electrons, is formed so as to face the first electrode.
If moisture or oxygen enters the organic light emitting device, the service life the organic light emitting display can be reduced due to oxidation and/or detachment of electrode materials, luminescent efficiency can be lowered, and/or the color can be changed.
Thus, the manufacture of an organic light emitting display device typically comprises a sealing process to isolate the organic light emitting display device from the environment and to prevent the moisture from entering into the organic light emitting display device. Examples of such sealing processes include lamination methods and encapsulation methods. A lamination method laminates an organic polymer, such as a polyester (PET), on a top surface of the second electrode of the organic light emitting display device. An encapsulation method forms a cover or a cap comprising a metal or a glass including a desiccant, fills the organic light emitting display device under the cap or the cover with nitrogen gas, and then encapsulates an edge of the cap or the cover by using a sealant such as an epoxy resin.
However, these methods often do not completely block the damaging compounds, such as the externally originating moisture or oxygen, which can ruin the device, and thus these methods are often not applicable to active-matrix organic light emitting devices (AMOLED), which are particularly vulnerable to moisture. Moreover, manufacturing processes for performing these methods are typically complicated. In order to solve the aforementioned problems, a frit encapsulation method that increases adhesion between a device substrate and the cap by using a frit as the sealant, has been developed.
The frit encapsulation method coats the frit on a glass substrate and seals an organic light emitting display device, thereby more efficiently protecting the organic light emitting display device since a gap between the device substrate and the cap is completely sealed.
The frit encapsulation method coats the frit on each sealing unit of an organic light emitting display device, and irradiates and seals the frit of each sealing unit with a moving laser irradiation device.
However, where the sealing operation involves only irradiating with a laser to harden the frit, a short-term detachment problem and a long-term reliability problem occur. To be more specific, in order to melt the frit without affecting a circumference, the sealing operation irradiates with a laser, thereby locally applying heat. The temperature of the heated area drops sharply, such that micro-cracks may be formed on the brittle frit. The micro-cracks cause a detachment problem. Also, the micro-cracks are likely to cause such detachment since the micro-cracks coalesce, as observed in a long-term reliability testing after sealing by the frit encapsulation method.